Oxygen consuming substances in European rivers

In European rivers, oxygen consuming substances decreased over the period 1992 to 2021. Biochemical oxygen demand (BOD) fell to half of the 1992 level, but has remained steady at around 2.8mgO₂/l since 2010. Ammonium concentrations fell to 20% of the 1992 level. After 2014, the level stabilised around 110µgN/l. The decrease in BOD and ammonium concentrations is a consequence of the improvement in wastewater treatment. Read more